At present, the fabricating method of the flexible OLED devices are usually used glass substrate as a supporter and for med by the following major steps: (1) coating a layer of special rubber material on the surface of the glass substrate, or depositing a layer of inorganic material as a sacrificial layer; (2) coating monomer, polymer or the mixed solution of the monomer and the prepolymer on the sacrificial layer, and polymerized the monomer into a flexible film by a process such as baking; (3) depositing a water-oxygen barrier layer on the surface of the flexible film layer; (4) performing array fabrication, evaporation and encapsulation process to complete the fabricating of the flexible OLED device; (5) after completion of fabricating, by using laser or baking method to make the sacrificial layer decomposition or softening, and then separating the flexible OLED device and the glass substrate by a smaller external force.
However, the above-mentioned conventional technology has many drawbacks: (a) during the preparation of the flexible film layer, the gas is easily mixed between the flexible film layer and the glass substrate, bubbles are generated during the later array process and the pre-deposition baking process, the generation of bubble will lead to damage the mask during the light irradiation defects of the array process and the evaporation process; (b) the flexible OLED device is irradiated by laser light, and a large amount of heat is generated on the surface of the flexible OLED device, which will cause thermal damage risk to the flexible OLED device. (c) the major material of the flexible film layer is polymer, having a large thermal expansion coefficient different from that of the metal electrode located on the surface thereof, and there is easy to have a peeling risk for the metal electrode and the flexible film layer; (d) during the laser irradiation, the laser may pass through the glass substrate and affect the organic light-emitting materials on the glass substrate, such as decomposition, crystallization, especially has more obvious affect to the bottom emitting device; (e) the price of the laser equipment is high so that large amount of cost for the production line is needed.
Although a carrier substrate made of a water-proof breathable material can be used to overcome the above-mentioned bubble problem currently, in this technology approach, it is necessary to prepare the flexible film layer in advance and then use an adhesive to adhere to the surface of the carrier substrate; Since there are many pores on the substrate for the release of bubbles, so the flexible film cannot be formed by directly coating on the carrier substrate, it can only take the bonding process to adhesive the flexible substrate and the carrier substrate, not only increases the complexity of the process, the flexibility of the flexible film layer has also been a huge challenge; and, due to the high temperature up to 450° C. to the flexible film during the array process, and because of the transmission property of the carrier substrate and the problem of scattering to the laser irradiation, making this carrier substrate is not suitable for laser lift-off, it can only use heating or mechanical lift-off, but also cause the problem of cleaning adhesive residue, so the technical approach has a high requirement to the carrier substrate and the adhesive.
Therefore, in the peeling process of the flexible OLED device and the carrier substrate, it urgently needs to adopt a method having less impact to the flexible OLED device to improve product yield.